In many communications applications, a signal is distorted by the hardware and channel over which the signal passes. An example where distortion occurs is a transmission system in a phone loop. Any signal, such as video, voice or data, passing through the phone loop, is subjected to the distortion introduced by the loop.
One prior art technique for eliminating noise in communications systems is taught in U.S. Pat. No. 5,251,328. The disclosed technique predistorts the amplitude of a transmitted signal in a manner which compensates for the amplitude distortion introduced in a portion of the communication channel.
Since a phone loop is formed by available equipment each time a call is placed, the distortion introduced will differ depending upon what equipment is utilized when the call is completed. Accordingly, since the distortion is not predetermined, compensation for distortion also cannot be predetermined.
It would be desirable to have a distortion compensation technique to ascertain the distortion introduced by a communications system so that information transmitted over the communication system, such as voice or data, could be predistorted/postdistorted such that the output signal would be distortion free.